A content provider usually protects contents such as music, movies, pictures, games etc. prior to transmission to users to avoid the unauthorized use, duplication and distribution of the content. Protection is generally performed using encryption and only the users that have the right decryption key(s) are able to decrypt and to consume the content. In order to allow flexibility in the way content is distributed, rights objects are used to define how content is allowed to be used. For example, a rights object might define the time period during which the user i.e. the receiver may use the content. Typically, the rights object will contain and protect the keys used to decrypt the provided content. An authorized user e.g. a previous purchaser is allowed to consume the content since he or she already has the correct rights object and the right key(s). It often occurs that the authorized user desires or needs to extend and/or upgrade the rights object. Typical causes include the following cases:                The user wants to get more permissions, e.g. to be able to print a picture in addition to displaying it on a screen.        The user wants to view the content a few times more or for a longer time period. For subscription based services, this could imply subscription renewal.        The user wants to get access to a new version of the content when available (e.g. video with higher quality, software with enhanced functionalities, game with new features, etc).        
Most systems such as digital right management (DRM) systems and/or conditional access (CA) systems handle the above cases by issuing a new rights object with requested rights for the same or new content i.e. in case of new content version. The new rights object is normally independent of the old one.
Secure Content Exchange (SCE) specified by Open Mobile Alliance (OMA) provides support for upgrade of rights object as specified in OMA-TS-SCE-DRM, DRM Specification—SCE Extensions, available at URL:http//www.openmobilealiance.org. In the specifications it is described that a user can upload the existing rights object to the rights issuer, specify the desired changes and then get back an upgraded rights object, which replaces the previous one i.e. the old one must be removed from the user's device before the new one can be installed. In some cases it can be expected that multiple users belonging to a group or domain will request the same upgrade. One example is that subscribers to a TV channel need to get the new channel key when it changes without undesired interruption. Another example is users requesting a new version of content/software/game they already have. For that purpose, the provider needs to know whether a user has previously consumed content and/or purchased rights. One reason is that the provider wants to offer e.g. a “bonus system” to previous users. The provider can keep some records in a user database and manage that database. A drawback with this is that the provider who offers a large variety of content/software etc. needs a large user database and thus the management overhead is not neglectable.
A solution to the problem above could be to request users to present their existing rights objects to the provider or to the rights issuer so that no database records are necessary. However, a drawback is that the protocol used for that purpose is complex since the provider needs to verify that a user really owns the rights object. Otherwise there is a risk that a cheating user gets upgrade. The complexity of the protocol is further increased due to the need of securely conveying the current state of the rights object e.g. how may plays left, remaining duration for content rendering etc., to the provider.
Sometimes the upgrade need is the same for multiple subscribers or users that already belong to a common domain or group. In this case, the provider would issue a rights object or an upgraded rights object that is usable by the multiple users of the domain or group. Most systems e.g. DRM and CA systems support domain rights object but this requires the users/devices to joint the domain. If we consider thousands or even millions of people who have purchased a popular content e.g. a game, software, a TV channel etc., each has to run the join-domain protocol in order to get the domain group key. Management of such a large domain is difficult due to the complex protocol and/or due to large management overhead and security issues.